Comments on: Virgin Galactic did another glide test of SpaceShipTwo today. https://behindtheblack.com/behind-the-black/points-of-information/virgin-galactic-did-another-glide-test-of-spaceshiptwo-today/ Fri, 09 Aug 2013 10:22:56 +0000 hourly 1 https://wordpress.org/?v=6.9.4 By: Dick Eagleson https://behindtheblack.com/behind-the-black/points-of-information/virgin-galactic-did-another-glide-test-of-spaceshiptwo-today/#comment-102347 Fri, 09 Aug 2013 10:22:56 +0000 http://behindtheblack.com/?p=24268#comment-102347 I suspect the hybrid engine is not able to provide consistent combustion quality and thrust. Even the allegedly successful powered test flight back in May had a pretty obvious hiccup shortly after initial ignition. The video shows the engine’s exhaust flame disappearing for a fraction of a second after being lit and then reappearing after what might have been a second ignition sequence. Then there’s the ground-based engine test that exploded shortly after the flight test. That failure was supposedly deliberately induced, but one’s skepticism about this official story only increases as each additional day passes with no second powered flight test.

The problems with this engine are probably traceable to the synthetic rubber fuel grain employed. This grain doesn’t seem to burn very evenly, producing a lot of smoke and spitting out sizable chunks of the grain as it runs. I would think that smoother, cleaner operation might be had by switching to a paraffin wax-based grain. Maybe all of this delay is owing to Scaled/Virgin having bitten the bullet and abandoned the trouble-plagued rubber grain for something else. If this is so, I wouldn’t anticipate either any further powered flight tests in 2013 or revenue service starting sooner than 2015.

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